National Dental Examining Board of Canada (NDEB) Practice Exam 2026 - Free NDEB Practice Questions and Study Guide

Nitrous oxide, also known as laughing gas, is commonly used as an analgesic to help relieve pain and anxiety during medical procedures. However, it can sometimes cause side effects, including ringing in the ears. This is because nitrous oxide can increase pressure in the middle ear, leading to a feeling of fullness and potential ringing or buzzing sounds. The other options, such as allergic reaction and decreased oxygen levels, may also produce different symptoms but are not directly related to the use of nitrous oxide. In addition, while sedation can cause side effects, such as dizziness or drowsiness, it is not a known direct cause of ringing in the ears. Therefore, the best explanation for why nitrous oxide may produce ringing in the ears is due to the increased pressure in the middle ear.